Earnings Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Earnings Per Share [Abstract]
Net earnings from continuing operations		$ 90,456	$ 71,841	$ 73,079
Less: Earnings allocated to unvested restricted stock	[1]	(1,067)	(690)	(819)
Net earnings allocated to common shares		$ 89,389	$ 71,151	$ 72,260
Weighted-average basic shares and unvested restricted stock outstanding (shares)		121,598	120,385	103,035
Weighted-average unvested restricted stock outstanding (shares)		(1,392)	(1,133)	(1,122)
Weighted-average basic shares outstanding (shares)		120,206	119,252	101,913
Basic net income per share (usd per share)		$ 0.74	$ 0.60	$ 0.71
Net earnings from continuing operations allocated to common shares		$ 89,389	$ 71,151	$ 72,260
Diluted net income per share (usd per share)		$ 0.74	$ 0.60	$ 0.71

[1] Represents cash dividends paid to holders of unvested restricted stock, net of estimated forfeitures, plus undistributed earnings amounts available to holders of unvested restricted stock, if any.